Tire pressure alarm



y 5, 1965 F. A. HOWARD 3,185,960

TIRE PRESSURE ALARM Original Filed May 16, 1956 4 Sheets-Sheet 1 w TH-43 4 4o 39 7\ 4.

I'll/I II 1 P W I777] I Q 44 4 38 8 lu I Frank A. Howard, InventorFigure I May 25, 1965 F. A. HOWARD TIRE PRESSURE ALARM Original FiledMay 16, 1956 Figure 2 4 Sheets-Sheet 2 Frank A. Howard, InventorAttorneys 4 Sheets-Sheet 3 Frank A. Howard, Inventor H? A orneys May 25,1965 F. A. HOWARD TIRE rnnssuma ALARM A7 a, f

Figure 3 Figure 4 May 25, 1965 F. A. HOWARD TIRE PRESSURE ALARM 4Sheets-Sheet 4 Original Filed May 16, 1956 United States Patent Myinvention relates to improvements in pneumatic tires. In my copendingapplication Serial No. 134,957, now United States Patent No. 2,811,189,issued October 29, 1957, I have showna strong and durable type of safetyring used in combination with a tubeless tire to carry the load for ashort time in the event of sudden tire failure,

as by blowout. In my copending application Serial No.

569,074, now United States Patent No. 2,934,127, issued April 26, 1960,I have shown a dual tire with a similar safety ring used as an innertire which is cut off from the outer tire chamber by a dual inflationvalve which prevents escape of air from the inner tire ondeflation ofthe outer tire. This application is adivision of my pendingapplicationserial No. 585,223, now United States Patent No. 2,969,824issued January 31, 1961.

In my present application I have shown an improved dual-tire,dual-valve, construction embodying a deflation alarm which gives noticeof loss of pressure in the outer tire. My present invention will befully understood from the following specification, taken in connectionwith the fied valve cap deflation alarm device showing the manner inwhich the electrical contacts are calibrated. 1

FIGURE 4 is a diagram of the electrical circuits used in the deflationalarm system.

FIGURE is 'a cross-section of a modified tire construction using acomplete inner tube inside thesafety ring. FIGURE 6 is an enlargedfragmentary section of the metal fitting which is used to deliver air tothe outer tire chamber.

Referring to FIGURE 1, numeral 1 indicates a onepiece, drop-center metalrim carried by a demo'untable metal disk wheel 2 which is detachablysecured to the wheel hub and to the brake drum 3 carried by the wheelhub. The mounting arrangements are commonly a plurality of wheel studsmounted inthe hub or brake drum.

For the purposes of my invention one such mounting stud, designated 4,is also used to carry the live wire of the deflation alarm circuit, aswill later appear.

There is mounted on the rim 1 a straight-side tubeless tire 5 ofordinary construction and an inner tire comprising a torus 6 having across section corresponding to the form of the inverted Greek capitalletterom'ega, the marginal channels 6a of which embrace the beads of thetire 5, as shown and described in my earlier-filed applications referredto. The torus 6 is customarily made of two plies of rubber-coated cordfabric vulcanized together in a mold. In FIGURE 1 I have shown the openbottom or inner circumference of the fabric ring 6 closed by a strip 7of rubber vulcanized or cemented at its margins to the inner marginalportions of the safety ring 6. The strip 7 thus converts the safety ringinto a complete airtight torus, but it will be observed that the bottomstrip 7 seats directly on the rim 1 save at its margins Where it seatsagainst and is bonded to the omega ring 6. Although 3,185,960 PatentedMay 25, 1965 "ice the strip 7 therefore prevents leakage of air underthe the beads from within the inner chamber formed by the safety ring 6,the ring itself still functions as before to carry the load in the eventof failure or deflation of the tire 5, and utilizes the inextensiblebeads of the tire 5 as the anchorage which holds the safety ring firmlyon the bead seats of the rim 1. Thus the bottom strip 7 may be regardedfunctionally and structurally as nothing more than an auxiliary seal toprevent air from leaking out under the channels of the ring.Accordingly, the bottom strip 7 may be of relatively thin sheet-rubberwithout reinforcement. In place of the rubber strip 7 I may use aseparate complete inner tubeof sheet-rubber, as shown at 67 in FIGURE.5. The safety ring6, the tire beads, and

the rim, carry all mechanical stresses, and the inner tube 67 has thesole function of forming a complete inner air barrier which unfailinglyholds air in the inner tire chamber in the event of puncture or failureof the outer tire casing and also in the event of air leakage under thebeads.

For use with the dual tire construction described, I employ a dualinflation valve designated 8, the barrel 8a of which is mounted inopening 1a in rim 1, shown in detail in FIGURE 2. Where the strip 7 isused, as shown in FIGURE 1, this dual valve is secured first in thatstrip. A moulded rubber duct or conduit 9, sufficiently rigid to avoidcollapsing the air channel 10 under external air pressure, connects thebore of a metal fitting 12 which passes through the safety ring 6 with aflat circular head 13 which forms the air connection to the dual valve.The rubber head 13 is gripped between the metal head 14 of the threadednipple 15, and the metal head 16 'of the valve body 8. Where the innerstrip 7 or complete inner tube 67 is used, the rubber head 13 seats onthe strip ortube' and forms an airtight joint with it when the nippleand valve body are screwed together. The mating external threads of thenipple 15 and internal threads of the valve body 8 are interrupted(breech block type) threads, having'multiple interruptions wide enoughangularly so that at any angular position there is an axial passage suchas the passage 17 through the threads and connecting the groove 13 inthe lower end of the threaded portion of the valve body with a mouldedgroove 19 in the fiat head 13 which in turn connects with the airpassage 10 to the metal fitting 12. The operating parts of the dualvalve are assembled in a single removable valve core. This core has theusual core-nut 20 threaded into the open end of the valve body 8. Thenut 20 carries a hollow sheet metal cone frustum 21 with the main valveseat at its open inner end. A central valve stem 22 carries the movableobturating element of thevalve in the form of a valve head 23 whichcloses this open end and is held against its seat by the valve spring24. The valve core cone 21 also carries a cylindrical extension 25 whichloosely fits the bore of the nipple 15. The extension 25 also ends in acone frustum, the open outer end of which is closed by a spring-pressedvalve 26. The inner end of the stem of the valve 26 clears the upper endof the stem 22 of the main valve 23, so that there may be slight openingof valve 23 before valve 26 is pushed open.

To seal the end of the cylindrical valve core extension 25 in the openend of the nipple 15, a rubber ring gasket 28 of considerable depth maybe confined between a shoulder on the end of the cylindrical valve coreextension 25 and a flange in the open end of the nipple 15.

The cylindrical valve core extension 25 has perforations which registerwith the groove 18, so that the chamber within the valve core betweenthe main valve 23 and the outer valve 26 communicates with the airpassages 17, 19, 10 and thus with the outer tire chamber through thehole in the metal fitting 12 shown in FIGURE 6. The

stem 22 of the main valve 23 may be made of hollow wire, so as toprovide a minute capillary bore extending from one end to the other ofthe valve stem. It will be understood that while this method ofby-passing the valve 23 through a very small passage has specialadvantages, as will later appear, the by-pass may be accomplished inother ways, as for example by a minute hole through the valve head.

For cooperation with the form of dual valve above described, I may use acup-shaped valve cap having a circuit closing device in the form ofself-contained pressuresensitive element capable of closing an electriccircuit. Such a valve cap is designated 29 in FIGURE 2. It is threadedonto the open end of the valve 8 in the usual way. Inside the valve capthere is a special form of rubber sealing gasket 3t? in the form of athick disk with a neck 3]. which extends into the bore of the valve 8and is surrounded by a small metal ferrule 32 which seats on the outerend of the valve core nut 23 when the disk itself seats on the open endof the valve 8. There is a central opening through the disk 39 and itsneck 31 and ferrule 32 which loosely fits around the projecting end ofthe valve stem 22. The rubber disk 36 is forced inward by the fiat baseof a stiff metal cone-frustum 33. A pressure-sensitive diaphragm in theform of a flexible metal, plastic, rubber, or mica disk 34 is grippedbetween soft insulating rings 35 in the margins of the base of the cone33. A metal button 36 fastened in the center of the pressure disk 34 isconnected by a thin flexible wire 37 with the live wire 38 of thedeflation alarm circuit. The base of the cone 33 has small perforationswhich register with the hole through the gasket 30, and the metal button36 rests with some slight pressure on this perforated central area ofthe cone base 33 when the parts are assembled. The valve cap 25" may beswelled outward to form an internal chamber which loosely surrounds thedisk 39 and the base of the cone 33, which are larger in diameter thanthe valve body 8. The end of the valve cap 29 is then domed andcentrally bored to receive the wire 33 and to bear on the top of theconical metal member 33. By this construction the valve cap 29 may bescrewed and unscrewed on the valve body without twisting the wire 38 andwithout turning the gasket disk 30. As the valve cap is screwed down itturns relatively freely on the outer end of the cone 33 and presses thecone base against the rubber disk 30, thus sealing the open mouth of thevalve body 8. At the same time the neck 31 of the disk 30 is compressedagainst the base of the ferrule 32 which bears on the end of the valvecore nut 20, and since the ferrule prevents radial expansion of the neck31, the axial pressure on the neck causes inward radial flow of therubber, so that the central bore through the disk contacts and sealsaround the end of the valve stem 22. This seal around the valve stem 22is thus created solely by inward radial flow of the rubber and there isno danger of opening the valve 23.

Referring to FIGURE 1, the wire 38 may be adhesively or mechanicallysecured to the Wheel disk 2 up to a point near the wheel stud 4. Theloose end of the wire near the wheel stud may be secured in a connectioncap 39 which snaps over the end of the insulating core of the wheel studand thus connects with an insulated central conductor 4a passing througha bore in the core of the wheel stud and terminating in an insulatedcontact button on the inner end of the stud. Once each revolution thiscontact wipes across a bow spring contact member 4-1 shown as supportedin a fixed stud which passes through a stationary flange 43, on thevehicle axle, which closes the open face of the brake drum and housesthe brake band 44 and its supporting and actuating mechanism. Thedeflation alarm circuit is shown in the electric circuit diagram FIGURE4. The contact 36 carried by the pressure-sensitive disk 34 grounds theline 38 when the contact bears on the base of the cone 33. The ground iseffected through the metallic contact between cap 29 and cone 33 at theopen end of the cap, and by the valve 8, thence through the rim of thedisk wheel in which the valve is fastened as shown in FIGURE 2.

The wires 38 from each valve cap pass through the connections 39, 4t),41, to a single line 45 in which there is interposed a manual cut-outswitch 46 and a second switch 47 which is mechanically connected withthe vehicle motor ignition switch 48 so as to turn oif and on with thatswitch. Beyond the switch 47 the line leads to the vehicle horn 49, thento the vehicle battery St), one side of which is grounded to the frameof the vehicle as usual. The vehicle horn 4) has the usual manualoperating switch or horn-button 51 which grounds the horn circuit in theusual way to sound the horn in a continuous note at will and isunaffected by the deflation alarm circuit. It will be noted, therefore,that while the vehicle horn is used as the tire deflation alarm, itactually gives a characteristically diflerent note when sounded throughthe deflation alarm circuit than when sounded manually.

In general, the purpose of the combination above described is to reducethe hazards involved in the use of pneumatic vehicle tires to such apoint that enforced vehicle stops, to make on-the-spot tire repairs orchanges, need no longer be contemplated. This avoids the need to carryin the vehicle at all times a spare wheel and tire, jack and accessorytools. To accomplish this re suit I have shown and described in theforegoing a combination including the following major elements.

First, a tubeless tire of conventional form.

Second, a strong and durable cord fabric safety ring Within this tire,the ring being of the cross section of the Greek capital letter omega.The channel-shaped margins of the ring embrace the eads of the tubelesstire so that these beads now have the function of anchoring and sealingthe margins of the safety ring as well as anchoring and sealing the tireitself on the rim. To provide additional insurance against complete tiredeflation through leakage of air under the tire beads or under thechannel margins of the safety ring, I may also close the open bottom ofthe safety ring with a thin air-impermeable strip of sheet rubber inwhich the dual inflation valve is fastened, or I may use a completeinner tube of thin sheet rubber.

Third, to permit simultaneous inflation and deflation of both the outerand inner chambers of the tire equipped with the safety ring, I haveshown a dual valve which holds air in the inner tire chamber if theouter chamber becomes deflated.

Fourth, should the air pressure in the outer tire chamber drop to a lowlevel for any reason, the inner tire chamber is capable of carrying theload of the moving vehicle for a considerable time. It is desirable,however, to warn the driver of loss of pressure in the outer chamber sothat he may avoid prolonged high speed driving and take the firstconvenient opportunity to have the tire repaired. This warning is givenby a deflation alarm circuit which sounds the horn of the moving vehiclewith a characteristic pulsing or vibrating note when the pressure in theouter tire chamber falls below a predetermined minimum. The manualcut-out switch in the alarm circuit can be at once opened to avoidcontinued sounding of the vehicle horn.

The manner of assembly and operation of the combination which attainsthe final results above described is as follows:

The inflation valve 8 is fastened in the bottom strip 7 of the safetyring before the ring is mounted on the beads of the tire. At the timethe valve is so mounted, the conduit 9 connecting the valve with themetal fitting 12 may be either left free or cemented to the inside ofsafety ring. If the complete inner tube 67 (FIGURE 5) is used, the valveti and fitting 12 are first installed in the inner tube, and the innertube then put in the safety ring and secured by the fitting 12 whichpasses through a hole the chamber.

in the ring. The mounting of the tire, with its safety ring, onthe rim 1is carried out just as though the safety ring were an ordinary innertube. Inflation is carried out as thefinal part of the mountingoperation by applying an air pressure connection to the open end of thevalve 8, thus forcing the tire beads outwardly until they reach the rimflanges. This may be done before the valve core is inserted in thevalve. If the valve core is in place, the stud in the center of thestandard tire inflation hose connection operates in the usual waytopress the valve stem 22 inward, which opens both the outer valve 23and the inner valve 26 so'that air is admitted freely and simultaneouslyboth to the inner and outer tire chambers. By constricting the bore inthe metal fitting 12 the inner chamber may, if desired, be causedto'inflate faster 'thantheouter chamber but the inflation pressures inthe two chambers will equalize as the inflation rate tapers off.

When the air hose is removedfrom the valvethere will be a very smallflow of air outward from the outer tire chamber through the capillarybore in the valve stem 22 This may reducethe air pressure in the outertire chamber below that in the inner chamber by a small controllableamount, which is itself usually desirable. The valve cap 29, which isalways conveniently at handbecause it is held by the loose end of thewire-38, can be screwed on rapidly enough to prevent excessive loss ofpressure from the outer Becauseof the clearance between the end of thevalve stem 22 and the stem of the valve 26 it is also possible to bleedair from the outer tire chamber by slightly depressing the valve stem22, without losing air from the inner chamber. As the valve cap isscrewed up tight it seals both the open end of the valve in the usualway, and also separately seals the end of the valvestem 22. The seepageof air through the capillary bore of the valve stem 22 builds up apressure under the pressuresensitive disk 34, distending this disk tohold the contact button 36 free of the metal base of the cone 33. Thusthe ground connection through the valve and rim to the vehicle frame isbroken.

Tire mounting and inflation is normally carried out only when the engineis stopped, so the deflation alarm circuit will then be open at theswitch 47 which is mechanically operated by motion of the vehicleignition switch 48.

It will be noted that the dual valve 8 and valve cap 29 provide twoseparate seals for both inner and outer tire chambers. The outer tirechamber is sealed both by the disk 30 seating upon the open end of thevalve body 8, and by the compression of the rubber in the neck 31 of thedisk around the valve stem 22. If either of these two seals is perfectthere can be no loss of pressure from the outer tire chamber so long asthe valve 23 is tight. Loss of air from the inner tire chamber to theouter tire chamber is prevented only by valve 26, but loss of pressurefrom the latter chamber to atmosphere is still prevented by the twoseals provided by the valve cap 29.

Because of the relatively large depth of the rubber ring washer 28 greataccuracy in the dimensions of the parts is not necessary. A reliableseal at this point may be obtained when the valve cone 21 seats on itsconical seat in the valve body, as the nut is screwed in. In the eventthe strip 7 is not employed, but only the omega ring itself, a shorternipple 15 may be used, or a gasket of the same thickness as the missingstrip 7 may be inserted. In either case it will be clear that the valve8 is sealed in the rim 1 by an inner gasket under the head 16 andsecured by an outer ring nut, as is standard practice in mounting avalve in a tubeless tire. It will also be seen that the dual valve coreis bodily removable as a unit and should any part fail to seal oroperate satisfactorily the valve core may be economically replacedrather than repaired.

In FIGURE 3 I have shown a slightly modified form of valve cap and haveshown how the pressure-sensitive switch is calibrated to remain openuntil the outer tire chamber pressure falls to the predetermined limit.In FIGURE 3 the valve cap is designated 52, the metal cone 53, and thepressure-sensitive disk 54. The cone 53 is flanged over slightly at thetop as shown at 55 to lock the cap and cone loosely together. The valvecap rubber gasket 56 has a hole in the center which exposes the-centerof the base of the cone 53. In or near this exposed center'of the base acircle of holes 57 may be punched whichhas the dual result ofensuringfree access of air-from the valve to the face of the disk 54 andalso weakening the'center of the cone base to make it easily bent. ,Thedisk 54 is mounted between soft gasket rings 58 and carries a metalcontact rivet 59 in its center which also secures the wire 37. Theexternal wire 38 joins the wire 37 in a connecting plug 61 which isexternally serrated to make sure that'the outer face of the disk 54 isalways exposed to atmospheric pressure. The cone 53 may be assembled asa single unit with the disk gasket 56 by a metal ring 62 flanged overtop and bottom to grip the entire assembly firmly together andespecially to make certain "that there will be no leakage of air betweenthe .parts of the assembly. The valve cap 52 is expanded to accommodatethe assembly, whichfits loosely within the cap.

To calibrate the deflation alarm switch, the valve cap is screwed on adummy valve stem 63 which forms part of a fixture including an airpressure connection 64 terminating in a self-sealing rubber head 65. Inthe open end of the dummy valve '63 there is mounted a heavy centralstud 66. As the valve cap 52 is threaded down on the stem '63, the stud66 comes into contact with the center of the base of the metal cone 53,and, on continued turning of the valve cap, the stud bends upward thiscentral area inside the circle of weakening punch holes 57.

Assuming that the air pressure within the connection 64 is held at somepredetermined level, say 15 lbs. per square inch, the disk 54 will bedistended by this pressure on its face so that the rivet 59 does notcontact the center of the cone base. The deflation alarm circuit istherefore open at this point. As the valve cap is screwed down and stud66 bends the weakened center of the cone base inward, however, contactwill be reestablished and the alarm circuit thus closed. By thisprocedure the valve cap alarm device will have been calibrated so thatit will thereafter hold the circuit open so long as the pressure underthe disk 54 exceeds 15 lbs., but will permit the circuit to close whenthe pressure drops below that point. As will be seen in FIG- URE 2, theby-pass through the valve 23 provided by the capillary bore of the valvestem 22 will hold the pressure under the disk 34 or 54 at the levelexisting in the outer tire chamber.

Valve cap deflation alarm devices calibrated for various pressure, asabove described, may be carried instock by tire and accessory dealersand supplied on demand to suit the wishes of any user. Because of thewide variations in service of vehicles the safe minimum tire pressurevaries, even with tires of the same size. For convenience in changingvalve caps the connection plug 61 (FIGURE 3) between the valve cap andthe wire 38 may be made readily removable.

It will be seen that since both the dual valve core and the valve capwith its self-contained pressure-sensitive element are separate,relatively cheap standardized units which can be distributed nationally,the deflation alarm system does not depend upon expert maintenance butrather contemplates instead replacement of its two working components,if they should need servicing.

While I have shown and described in the annexed drawings and in thesespecifications many details of construction and arrangement of thevarious components of my improved dual-tire, dual-valve and deflationalarm system, it will be understood that this is all for the purpose ofmaking the invention as clear as possible and that the invention is notto be regarded as limited to any of the details described andillustrated save in so far as such limitations are included within theterms of the appended claims, for obvious modifications will occur toone skilled in the art.

What I claim is:

1. A pneumatic tire deflation alarm system for a vehicle comprising incombination a wheel, a wheel hub having outer and inner faces, a circleof threaded studs mounted in the hub for securing the wheel to the outerface thereof, one of said studs having an opening therein, electricalcontacts carried by the wheel, means for closing said contacts inresponse to a drop of the tire inflation pressure to a predeterminedpressure, an insulated electrical conductor passing through said studopening and having an insulated electrical contact adjacent the innerface of the hub and moving therewith, an electrical conductor connectingthe electrical contacts carried by the wheel to said insulatedconductor, a stationary electrical contact carried by the vehicle andlying in the path of rotation of the contact on the inner face of thehub, and an alarm circuit carried by the vehicle and adapted to beenergized when the electrical contacts carried by the wheel are closedin response to the drop of the tire inflation pressure to thepredetermined pressure and the insulated contact on the inner face ofthe hub and the stationary contact are intermittently closed duringrevolution of the wheel.

2. A pneumatic tire deflation alarm device comprising in combination atubular inflation valve having an inner end portion for connection to atire and an open outer end portion, said valve having an automaticinwardly o ening check valve member for admitting free ingress of airthrough the open outer end portion of the valve in order to inflate thetire and for blocking egress of air from the tire after the tire hasbeen inflated, said check valve member having a minute opening forbypassing the same, a removable valve cap for closing the open outer endportion of the inflation valve, a pressure-sensitive switch operativelyconnected with the interior of said valve cap, said switch beingactuated in response to pressure transmitted through said minuteopening, and an alarm system connected to said switch and activated uponthe response thereof.

3. In combination, a vehicle wheel having a rim portion with an openingtherein, said rim portion being adapted to carry a pneumatic tirethereon, an inflation valve for said tire having a barrel portionmounted in said opening in said rim, and a movable obturating elementdisposed in said barrel portion, said valve having a minute opening forbypassing said obturating element, a removable cup-shaped valve cap forclosing the outer end of said barrel portion, a pressure sensitivecircuit closing device contained Within said valve cap being sensitiveto a predetermined tire pressure communicated to it through said minuteopening, and a flexible electrical conductor for connecting the circuitclosing device to an alarm device, said conductor being attached to saidwheel and retaining said valve cap thereto.

References Eited by the Examiner UNITED STATES PATENTS 1,800,196 4/31Bennett 340-48 2,135,303 11/38 Greene 340--58 2,331,571 10/43 Risser200-61.25 2,562,862 7/51 Gunter 34058 X 2,716,167 8/55 Jacobus 200-61.252,729,712 1/56 Sprague 200-6125 2,966,563 12/60 Bobenhausen 340-58 XNEIL C. READ, Primary Examiner.

BENNETT G. MILLER, Examiner.

1. A PNEUMATIC TIRE DEFLATION ALARM SYSTEM FOR A VEHICLE COMPRISING INCOMBINATION A WHEEL, A WHEEL HUB HAVING OUTER AND INNER FACES, A CIRCLEOF THREADED STUDS MOUNTED IN THE HUB FOR SECURING THE WHEEL OF THE OUTERFACE THEREOF, ONE OF SAID STUDS HAVING AN OPENING THEREIN, ELECTRICALCONTACTS CARRIED BY THE WHEEL, MEANS FOR CLOSING SAID CONTACTS INRESPONSE TO A DROP OF THE TIRE INFLATION PRESSURE TO A PREDETERMINEDPRESSURE, AN INSULATED ELECTRICAL CONDUCTOR PASSING THROUGH SAID STUDOPENING AND HAVING AN INSULATED ELECTRICAL CONTACT ADJACENT THE INNERFACE OF THE HUB AND MOVING THEREWITH, AN ELECTRICAL CONDUCTOR CONNECTINGTHE ELECTRICAL CONTACTS CARRIED BY THE WHEEL OF SAID INSULATEDCONDUCTOR, A STATIONARY ELECTRICAL CONTACT CARRIED BY THE VEHICLE ANDLYING IN THE PATH OF ROTATION OF THE CONTACT ON THE INNER FACE OF THEHUB, AND AN ALARM CIRCUIT CARRIED BY THE VEHICLE AND ADAPTED TO BEENERGIZED WHEN THE ELECTRICAL CONTACTS CARRIED BY THE WHEEL ARE CLOSEDIN RESPONSE TO THE DROP OF THE TIRE INFLATION PRESSURE TO THEPREDETERMINED PRESSURE AND THE INSULATED CONTACT ON THE INNER FACE OFTHE HUB